In all honesty, I started by wearing solid colours and acting out a PMC, or if I was feeling really creative, a Human Terrain System specialist or intelligence agency guy. I was uncomfortable dressing up as a soldier when I worked so closely with them. As I got more into it, and as they started to think it was cool, I relaxed and now have no problem playing milsim in whatever role. Though a certain ex-HH-60H sailor made me promise her that someday I would be a CSAR guy.
Views are my own.